I tried searching but the maximum date range is 1 year. Are there any detrimental effects in using 100LL in engines other than chainsaws....typically engines with valves? The engines in question are the 4-mix in the BR600 & KM110 powerhead. Briggs 8HP horizontal shaft in a Trac Vac Kawasaki 15HP FH430V in my riding mower Vanguard 6HP in my pressure washer. The one engine I'm most concerned with is my 20HP Honda Twin in my generator, GX620. I'm not dead set on using the 100LL in these, especially the generator but want to ask about any issues I may have since they are not terribly high in compression. I did use the avgas in my KM110 and after a tankful it does run fine after I leaned it out slightly. All tips and criticism appreciated.